<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        #div_1,#div_2,#div_n{
            width: 200px;
            height: 200px;
            /* position: absolute; */
        }
        #div_n{
            top: 50px;
            left: 50px;
            background: red;
            /* position: relative; */
        }
        #div_1{
            top: 60px;
            left: 60px;
            background: green;
            /* position: absolute; */
        }
        #div_2{
            background: blue;
            top: 30px;
            left: 30px;
            position: absolute;

        }
    </style>
</head>
<body>
    <div id="div_n">
        <div id="div_1">
            <div id="div_2"></div>
        </div>
    </div>
</body>
</html>